This invention relates to the field of electrolytic production of aluminum in a cryolite-alumina melt, more particularly, to an activated lithium-containing carbon anode used for producing aluminum metal.
At the present, alumina as raw material is usually dissolved in the molten cryolite, and aluminum metal is produced from the cryolite-alumina melt during the electrolytic process. The anode used in the industrial or commercial production is made of carbon. Unfortunately, it has happened that an anode overvoltage on said carbon anode is shown about 400-600 mV due to the slowness of the reaction between oxygen ions and said anode. This anode overvoltage amounts up to 9-14% of the electrolytic bath voltage and causes a high consumption of electrolytic energy during the production of aluminum.
In the prior art, lithium compounds are usually added directly into the electrolyte to improve the properties of the electrolyte, thus elevating the electric current efficiency. However, the method of adding lithium into the electrolyte brings about significant amount of loss of lithium compound and especially the loss of volatilization from the electrolyte. At the same time, lithium compounds can not be distributed homogeneously in said electrolyte.
The objective of this invention is to provide an activated carbon anode having the different components from the ordinary anode, which can decrease the anode overvoltage, and characterized by lithium present in the anode.Thus lithium compounds will be dissolved slowly and evenly in the electrolyte as the carbon anode is consumed. Not only can the properties of electrolyte be improved, but also the electric current effeciency can be increased and disadvantages of the prior art in the industrial production of aluminum metal can be eliminated.